A brief introductory paper prepared by the New Zealand Chestnut Council, 2000

INTRODUCTION

The chestnut is probably the most important nut crop found throughout the temperate zone, worldwide.
With species indigenous to all three continents the chestnut has long been cultivated and consumed
throughout Asia, Europe and America.

In the Mediterranean region, chestnuts have been cultivated for at least 3,000 years. The ancient Greeks
are thought to have been among the first to cultivate the chestnut, introducing the European chestnut
(Castanea sativa) from Asia minor, via Turkey, to S. Europe and N. Africa. The Romans were later
responsible for extending the cultivation of C. sativa into northwest and central Europe and it was the
Romans who named chestnuts "Castanea", possibly after the name of the town where chestnuts were once
very common. It is thought that the word chestnut is an English corruption of the original Latin. In Asia,
the Japanese chestnut (C. crenata) has been cultivated at least since the 11th century, and the Chinese
chestnut (C. mollissima) possibly for 2-6,000 years. In the US, the American chestnut (C. dentata) was
once a major component of the indigenous forests.

Chestnuts were first introduced to New Zealand by some of the earliest European settlers. Today you can
still find old, often forgotten trees scattered throughout much of New Zealand, often in the most unexpected
places. Most are C. sativa or C. crenata, or seedling hybrids of the two. There are very few named,
overseas chestnut cultivars to be found in New Zealand as necessarily strict quarantine requirements make
the importing of overseas material extremely difficult, so as to avoid the risk of introducing overseas pests
and diseases (such as chestnut blight and gall wasp) which would not only destroy our chestnut industry but
could also attack some of our own fruit and tree species.

Plant Type: Small to large deciduous trees - meaning that the trees loose their leaves and become
dormant to withstand cold winters. The large edible seeds are called chestnuts and are produced annually
on the tree inside a prickly case called a burr. In the autumn, when ripe, the burr splits open allowing the
chestnuts to fall free, onto the ground.

Uses: Production of nuts, hardwood timber and in overseas countries, hardwood timber and ground
durable posts from the naturally rot resistant heartwood.

Latin Name:Castanea

Botanical Family: Fagaceae - this is also the beech and oak tree family. All chestnut species are native
to northern hemisphere countries.

Species: Worldwide there are four main species along with several minor species. The four main species
that have been utilised by mankind for their various produce are:

1) Japanese chestnut - Castanea crenata - a small to medium sized tree (~10 m), which is typically multi
leadered and wide spreading. Some varieties have very large nuts (~40 g), which are nearly the size
of small potatoes. Nuts of this species typically have difficult to remove inner skins (pellicles). This
species is well adapted to wet and humid weather conditions and hot summers (~30oC). These trees
have been present in New Zealand since the early 1900's, particularly in the upper North Island
region.

2) Chinese chestnut - Castanea mollissima - a medium sized tree (~15 m), often multi branched and
wide spreading. Nuts usually have easy to remove inner skins and come in a wide range of sizes,
although typically smaller than the Japanese chestnut. At present the Chinese chestnut is a rare tree
in New Zealand, but recent imports may change this.

3) American chestnut - Castanea dentata - the largest growing (~30 m) and straightest trunked of all
the chestnut species, was once a prized timber tree in the USA before its demise due to the
devastating fungus disease called chestnut blight. Nuts are typically very small (~5 g), but quite sweet
tasting with easy to remove inner skins. This is a rare tree in New Zealand but recently has been
imported through quarantine.

4) European chestnut - Castanea sativa - a large growing (~20 m) and wide spreading tree which
originated from around Turkey and the Black Sea region of southern Russia. During Roman times
this very versatile and adaptable species was introduced to most present day European countries
where it has become naturalised, and today is a common part of the landscape in many regions. The
nuts are quite variable but superior fruiting varieties possess good size, sweet taste and have easy to
remove inner skins. This tree is the most commonly seen chestnut species in New Zealand where it
was introduced by the early settlers. This species is also known as the sweet chestnut or the Spanish
chestnut in English speaking countries.

Hybrids: Where the different species have been planted in close proximity to each other by man natural
hybrids between the species occur readily. This has occurred in several countries around the world including
New Zealand, where today large hybrid chestnut trees are common. Chestnut breeding programmes around
the world have deliberately hybridised the various species to create superior varieties for fruit and/or timber
production. European/Japanese hybrids are now the common commercial fruiting varieties in France,
Australia, New Zealand and the western USA. Japanese/Chinese hybrid varieties are now found in South
Korea and Japan. American/Chinese hybrid varieties are now found in the eastern USA along with even
more complex hybrids.

Food Value: Chestnuts have a quite remarkable nutritional composition that sets them apart from all other
nuts and makes them an outstanding food source which can be a dietary staple. The nuts are ~50% water
when fresh, which makes them highly perishable. Chestnuts are made up of primarily complex carbohydrate,
are low in protein (~5%) and are very low in fat (~1%), have reasonable quantities of vitamin C and
potassium, are very low in sodium and are free of gluten, oil and cholesterol. The protein is of very high
quality, comparable with eggs and is easily assimilated by the human body.

The flavour, texture and sweetness of the nuts from different chestnut species and varieties varies widely,
from tasteless and bland to very sweet and flavoursome.

To Eat: One must first remove the outer shell and inner bitter tasting skin to obtain the edible kernel and
although chestnuts can be eaten raw after peeling they are usually cooked in some way. Cooking methods
vary widely but simply can be done by boiling the in-shell nuts whole for half an hour and then cutting them
in half and scooping out the soft kernel flesh inside using a teaspoon. Another common way is to roast in-shell chestnuts in the oven, over hot embers or in the microwave, but you MUST pierce the shell with a
small cut or cut them in half beforehand with a knife to prevent them from exploding when they cook!
Specialised hand held chestnut peelers that remove the shell and inner skin together before cooking make
the tiresome task of peeling chestnuts quite easy and quick. (These are available in New Zealand). Once
you have peeled your chestnuts they may be cooked in a wide variety of ways - boiled, roasted, steamed,
microwaved, pureed, soups, stuffings, sweet desserts and so on. The nuts can also be dried and ground into
an excellent quality flour for bread, biscuits, gravies etc. Chestnuts are very diverse in their culinary uses
and many classic recipes are popular worldwide.

Worldwide Production and Consumption: Huge tonnages (currently estimated in excess of 470,000
t) are produced and traded annually worldwide, mainly among northern hemisphere countries. For much
of this century however, worldwide production has steadily declined, due mainly to disease, alternative land
use and population pressure.

At the beginning of this century France, for example, grew nearly 400,000 t of chestnuts, alone. By the
1960s this had dropped to only ~45,000 t, dropping further to ~25,000 t by the 1980s, and to only ~11,000
t by 1995. Italy, Europe's biggest chestnut producer and exporter has likewise dropped from over 300,000
t in the 1950s to only ~65,000 t by 1995.

Today, the world's top ten leading chestnut producers are, firstly, China, then Turkey, Korea, Italy, Japan,
Spain, Portugal, France, Greece and Albania, in descending order. Demand, even in most of these countries,
however, continues to outstrip supply. Despite being the fifth largest producer in the world, Japan imports
more than 33,000 t of chestnuts annually (more than 3 times its own production). In Europe, France
imports more than two-thirds of the total chestnuts consumed there. Significant tonnages are also traded
throughout the rest of Europe, the Americas (both North and South), Africa, Asia and the Middle East. The
top ten chestnut importing countries, worldwide, are currently Japan, then France, Hong Kong, Switzerland,
Brazil, USA, Germany, Austria, and UK and Italy (~70,999 t in total).

International chestnut prices have increased consistently over the last 20 years, fuelling the current renewed
interest in chestnuts. "New" chestnut producing countries are now starting to appear on the world stage.
The USA and some South American countries produce small quantities of chestnuts. Australia produces
~700 t (mostly for local consumption). Current New Zealand production is estimated at over 200 t. In both
New Zealand and Australia production is rising.

In New Zealand Today

Based on research and trials conducted largely by the North Island Chestnut Action Group, the NZ Tree
Crops Association, MAF and DSIR during the 1980's chestnut orchards today are being planted in New
Zealand as an export orientated high value nut crop for sale as fresh produce and/or for processing. The
chestnuts are produced from planned orchards of known performance based on grafted superior varieties.
The industry is barely 15 years old but experience to date with chestnuts as a commercial orchard crop in
New Zealand tells us the following:

Regions: Most producing orchards today have been established in the Waikato, Bay of Plenty and
Auckland areas. However, chestnut trees will grow successfully across most of New Zealand and there are
many new plantings established in Northland, Wairarapa, Levin and Canterbury.

Topography: Flat to gently sloping land is preferred for ease of operation, (especially mowing and
harvest).

Climate: A hot summer with maximum temperatures of at least 25-30oC to ripen the nuts. Regular
rainfall over the summer and autumn months to ensure that the nuts reach their optimum size, otherwise
irrigation may be required. Late spring frosts can be a problem in some regions by burning the new season
foliage.

Altitude: Chestnut trees will grow well vegetatively at high altitudes in New Zealand but may not fruit
at all or otherwise sporadically. These altitude limits for successful fruiting are still to be defined but could
be as low as 500 m above sea level.

Shelter: Although chestnut trees are reasonably wind hardy and demand a high light intensity to promote
female flower production, they grow and produce much better with effective shelter from the strong
prevailing winds that are common across much of New Zealand, especially over late spring and early
summer when new foliage is at its softest and prone to wind burn. Effective shelter is most needed when
the trees are first planted and over their next few years when vegetative growth is at its maximum. Ideally,
shelter lines should be planted 1-2 years before the orchard trees.

Orchard spacings: The most common spacing pattern is to initially plant the orchard at 6 x 6 m (256
trees/ha) and when the trees begin to intergrow to thin out the temporary trees to a final spacing of 12 x 12
m (64 trees/ha). Alternatively some growers plant at 12 x 12 m (64 trees/ha) particularly where the land
between the trees can be intercropped.

Varieties (or cultivars): The most commonly planted varieties are the Euro/Japanese hybrids which are
known by the following numbers - 1002, 1005 and 1015. All are characterised by rapid vegetative growth
when young and are early bearing. Nut production will commence in the second or third season after
planting if desired. To a much lesser degree there are plantings of the Japanese chestnut varieties Mayrick
King, Mayrick Queen and 902, which appear to crop more heavily in the warmer regions such as the coastal
Bay of Plenty and northern regions. The Japanese chestnut varieties often produce the largest nuts but the
trees are not always as hardy as the Euro/Japanese varieties.

All these varieties produce chestnuts that possess difficult to remove inner skins that are easiest to prepare
for cooking by peeling with the specialised chestnut peelers as described earlier.

Pollination: Chestnut trees require cross pollination from a different compatible variety to ensure good
nut production. This means that an orchard planting must contain at least two different pollen producing
varieties in a low ratio mix, such as 1:1 or 2:1. Pollination is carried out by wind and insects. Well
pollinated chestnut trees will produce 2 or 3 plump nuts per burr. Chestnut trees that are not cross
pollinated at all will still produce burrs every year but these will only contain 3 flattened empty shells lacking
kernels, or on occasion poorly formed nuts.

Fertiliser: Chestnut trees respond well to a balanced fertiliser programme, whether it be organic or
artificial. They need good supplies of nitrogen, potassium and magnesium in particular. Apply in the early
spring and again mid summer, but remember the maxim 'a little and often' rather than one heavy application
which can cause root burn and much of which is usually wasted.

Harvest: Chestnuts fall in the autumn and ideally should be gathered every day over peak nutfall because
of their highly perishable nature and their susceptibility to predation by possums and rats which relish the
nuts. Harvesting is usually done by hand, although there are now various mechanical or vacuum machines
of various sizes (some are tractor powered, others are smaller and backpack style).

Storage: Because of their highly perishable nature freshly harvested chestnuts must be cool stored
immediately at 0-2oC. To prevent dehydration under cool storage the chestnuts should also be placed into
ventilated plastic bags (containing small holes). For small quantities in the household this can be done by
keeping fresh chestnuts in the fridge, packed into ventilated plastic bags or the vegetable drawer. Once
coolstored fresh chestnuts may keep in good condition for up to six months or even longer dependant on
the level of fungal rot infection and the variety.

Packhouses: For orchards with chestnuts to sell there are industry registered packhouses that will store,
grade and pack the chestnuts for export to industry standards.

Marketing: For the New Zealand industry to continue competing successfully long term into world
markets focus must be on producing only top quality products, whether it be in processed or fresh nut sales.
Our strengths from a marketing perspective are: we have a clean green and uncrowded environment (where
high quality produce from organic production is easily achievable); New Zealand growers enjoy freedom
from the world's major chestnut pests and diseases; and being southern hemisphere producers are able to
provide a fresh product into the northern hemisphere in their off season.

Chestnuts are regarded as a very high health food product that few other foods can match, but few
consumers realise this. Marketing efforts should always capitalise and promote this highly desirable
attribute.

In the past, all growers belonging to the New Zealand Chestnut Council marketed their crop through
Chestnut Exports NZ Ltd (CENZ): a growers' owned and operated company formed especially to market
chestnuts for the New Zealand Chestnut Council. Today, a range of private companies process chestnuts.
Chestnuts are also marketed domestically.

Industry Organisation: There is a national growers association called the NZ Chestnut Council which
co-ordinates all aspects of the industry. Bimonthly newsletters are produced and there are numerous field
days for growers. Comprehensive information on growing chestnuts in New Zealand is available from the
Executive Director, Dr David Klinac, HortResearch Ruakura, Private Bag 3123, Hamilton. Phone [07] 858
4668, fax [07] 858 4700, or email info@nzcc.org.nz. Prospective growers, growers and anyone with an
interest in chestnuts are encouraged to become members of NZCC.

Yields and Returns: NZ Chestnuts are exported around the world and also sold in New Zealand.
Estimating grower returns and production levels per hectare is easier said than done, given the vagaries of
the market place from year to year and the wide variation in tree performance from one site to another.
However, growers gross returns (at gate) can range from $1.50-$3.00/kg depending on size or grade of the
nuts, with the larger or earlier-season nuts usually fetching a premium. Small nuts are difficult to sell at a
profit on the fresh fruit market and are utilised for processing into value added products. Harvesting costs
range from 50c to $1.00/kg depending on tree age. Given reasonable conditions most orchards are capable
of achieving around 4 tonnes/ha once the trees reach maturity by year 10. Average gross returns (calculated
at $2.50/kg average) at maturity would then be in the vicinity of $7,500/hectare.

Compared to many horticultural crops a chestnut orchard is cheap to establish and maintain, and has a low
time input requirement (except at harvest). This allows most orchard owners to follow additional vocations
as well.

Processing: Overseas chestnuts are readily processed into a wide range of user friendly long life products
that are designed for everyday consumption, and are available from the supermarket shelves. Continued
emphasis on processing (versus export of fresh nuts) is expected to continue. Overseas processed products
include peeled frozen free flow, canned whole peeled chestnuts, vacuum packed whole peeled chestnuts,
sugared confectionery, purees, ice-cream, baby foods, chips, yoghurts, dried whole chestnuts, flour for bread
and biscuits etc. Many products are sold on the health market for premium prices. By developing a range
of processed products the New Zealand Chestnut industry avoids the pitfall of over reliance on a single
market type (for example fresh nut) which could become over supplied at some stage thus crashing grower's
returns.

Diseases & Pests: Overseas there are many serious and crippling pests and diseases that often make
chestnut production uneconomic. New Zealand is indeed fortunate to be mainly free of most of these
serious problems and this is the reason for the strict border controls and lengthy quarantine periods placed
on the introduction of overseas chestnut plant material including seeds. If you travel overseas please do
NOT bring back any fresh chestnuts in your pocket as many of these pathogens are spread by contaminated
chestnuts that appear quite healthy. In New Zealand the main problems are:

Root rot caused by the soil-based fungal disease Phytophthora cinnamomi which usually kills the tree, (at
any age), and is more prevalent on heavier soil types. Trees can be infected at the nursery stage so ensure
your nursery supplier is certified as meeting the nursery standards as specified by the NZ Chestnut Council.
Control with fungicides is difficult, however the use of trunk injections or foliar sprays with phosphorous
acid as a preventative for healthy trees is currently under trial evaluation and showing promising results.
To reduce exposure to root rot diseases it is not recommended that orchards are established on poor
draining soils, prone to waterlogging.

Infection of the nuts while on the tree with the fungal diseases Phomopsis and Botrytis (and other fungi) can
lead to rotten nuts at harvest and can cause serious losses even under cool storage.

A native insect - the grass grub beetle, will eat the soft new season foliage of chestnut trees in the late spring
when they fly at dusk, often in quite staggering numbers. Young trees may be completely stripped.

Possums are especially damaging, eating the bark, leaves and breaking branches and relish eating the nuts
when they fall to the ground at harvest.

Rabbits and hares will eat the bark of young trees.

Propagation: Chestnut varieties are propagated by grafting or budding onto a seedling rootstock. To
help minimise graft incompatibility problems (where the upper part of the tree dies or becomes unthrifty
after rejecting the lower rootstock which remains alive) it is recommended that trees are grafted or budded
onto seedling rootstocks that have been grown from chestnut seed of the variety being propagated, and
which come from known problem-free seedlines, or from NZCC certified seed orchards. For example, to
propagate the variety '1005' are collected from 1005 trees as seed to be grown as seeding rootstocks and
then grafted or budded 1005 scions.

Organic Production: Is easily achievable with chestnut orcharding especially in the drier regions where
fungal problems are minimised. Alternative organically acceptable sources of fertiliser must be used. Weed
control must not include the use of chemical herbicides. To become a bona fide organic chestnut grower
strict guidelines as specified by the BIO-GRO NZ (P O Box 9693, Wellington) and DEMETER (P O Box
306, Napier) programmes must be followed. Contact The Soil & Health Association, P O Box 36 170,
Northcote, Auckland, or phone [09] 443 8435 for details.

Timber & Posts: Although regarded overseas as a valuable and versatile hardwood, very little work has
been done to ascertain the potential, quality and durability of New Zealand grown chestnut timber and posts.
Chestnut trees have the ability to coppice readily, which means they will regrow from the stump when cut
down.

False Chestnuts: Do not confuse true edible chestnuts with the semi-poisonous nuts of the commonly
seen ornamental flowering Horse Chestnut tree which fall at the same time in autumn and are of a similar
size, shape and colour. True edible chestnuts are readily recognisable from conkers (the nut of the common
name for Horse Chestnut) by the point at the top of the nut. Conkers have no point on their flattened
smooth tops.

Chinese water chestnuts, which are a common ingredient of Asian cooking, are grown beneath a swamp
loving sedge. This plant is not related at all to true chestnuts.

Good luck: If you would like more information about New Zealand chestnuts then you should subscribe
to the "Chestnutz News" newsletter, available to all members of the New Zealand Chestnut Council.

CONTACT THE NZCC

For further information about the New Zealand Chestnut Council, contact: